This program project grant (P01) application is a renewal of the current grant: Mechanisms and Interventions Addressing Serious Hazards of Transfusion and Cellular Therapies. This Program represents an integrative endeavor by the Emory University Center for Transfusion and Cellular Therapies (CTCT) which includes a group of physician-scientists dedicated to the advancement of the field of transfusion medicine and cellular therapies via basic, translational and clinical research, excellence in clinical care and teaching, and the education of future leaders and scientists. The investigators are grateful that the current 6 year funding period has allowed us to improve our synergistic interactions and make significant progress in the previously funded investigations. Furthermore, we believe that this renewal application represents a significantly improved set of interrelated projects. The central theme of this P01 renewal has been modified to be more consistent between projects, allowing greater cross-project interactions and synergy between investigators. We still address Serious Hazards of Transfusion, but our focus is on those hazards that occur in transfusion recipients following infusion of RBCs that have been stored for extended periods of time prior to transfusion (herein called storage-aged RBC [saRBCs]). These hazards include shortened RBC survival and alterations in NO-mediated vaso-responsiveness in adult recipients (Project 1), necrotizing enterocolitis (NEC) in neonatal patients (Project 2), altered alloimmune responsiveness in transplant patients (Project 3), and shortened RBC survival (Project 4). The primary goal of the Projects in this Program is to develop a panel of RBC biomarkers that identify RBCs that have entered a state of impaired functionality that not only predisposes these cells to reduced post-transfusion survival but leads to adverse effects in the transfusion recipient. While current evidence supports the contention that generally the longer RBCs are stored the less efficacious they will be and the more likely they are to cause adverse events, we believe that a simplistic formulation based on chronological storage age is ultimately counter-productive. Rather, transfusion efficacy and safety can be improved by utilizing biomarkers to test for the metabolic age of RBC units.